Compressed air circuit breaker with movable piston



ay 5, 1936- L. J. SAUDICOEUR 2,039,833

COMPRESSED AIR CIRCUIT BREAKER WITH MOVABLE PISTON Filed Feb. 25, 1955 Zbzzif 7, dazz Patented May 5, 1936 UNITED STATES PATENT OFFICE Louis Joseph Saudicoeur, Villeurbanne, France Application February 25, 1935, Serial No. 8,090

In France March 9, 1934 2 Claims.

Electric circuit-breakers are known in which the arc is blown out by compressed air produced during the opening operation of the circuitbreaker by means of a piston pump actuated at 5 the same time as the movable contact. In certain circuit-breakers of this type the piston and the movable contact are fixed on the same rod in such manner that the compression of air inside the cylinder of the pump by the piston last as long id as the separation of the contacts.

It is known that after extinction of the are it is necessary that the contacts be still further sepparated over a certain distance so as to ensure between said contacts a supplementary insulating gap. It is further recognized that during this second stage of the displacement of the movable contact it is possible, without any inconvenience, to diminish the intensity of the air blast on the contacts or even to suppress said blast altogether, and this permits a more rational utilization of the compressed air produced by the pump.

In accordance with the present invention this result is obtained by the use of a piston mounted loosely on the rod carrying the movable contact and held by means of a spring against a stop fixed on said rod, the displacement of said piston being arrested before the end of the displacement of said rod by means of an abatement fixed to the cylinder.

rected towards the arc through any convenient channel, for example by passing through the interior of the piston rod made hollow for this purpose. a

The invention and its aims and objects will be readily understood from the following descrip- 'tion, taken in connection with the accompanying drawing of one illustrative embodiment of the invention. s

In the drawing:

Fig. 1 is a vertical cross-sectional view oi. a circuit-breaker shown inclosed position and embodying one illustrative form of the invention.

Fig. 2 is a partial cross-sectional view of the same embodiment shown in operating position.

In the illustrative embodiment of the invention shown the circuit-breaker comprises fixed contact I with its corresponding sparking contact I moulded on a supporting insulator. It is further provided with hollow movable contact 2 in the axis of which is fixed its sparking contact 2. Between members 2 and 2' there is provided a convergent nozzle 3 made from insulating material. Members 2, 2' and 3 are fixed at the free extremity of hollow :rod 4 disposed in the interior The air compressed by the piston may be diof cylinder 5. Piston 6 mounted loosely on rod 4 forms with said cylinder 5 a pump projecting a blast of air against the are drawn out at break and resulting from the separation of sparking contacts l and 2. Spring i5 disposed inside cylinder it maintains piston 6 applied against projecting member of fiange l8 fixed on rod 4 and tends to displace said piston 6 together with said rod 4 towards the leit, separating at the same time the contacts and compressing air inside cylinder 5. Said pump is mounted on the second supporting insulator 'i..

At its extremity opposed to the contacts, said rod 4 is extended beyond piston 6 and carries at said extremity a connecting rod 8 mechanically operated through insulator 9 pivotally mounted on axis l0. Between said connecting rod 8 and said piston 6, rod 4 is provided with a series of apertures i I disposed near said piston at the side 01' flange l8. Beyond said apertures plug 2!! obturates hollow rod 4. In the left hand end of cylinder 5 is disposed the abutting member or cylindrical sleeve II the internal diameter of which is greater than the external diameter of flange l8 and smaller than the external diameter 01 piston 6.

The two terminals of the circuit-breaker shown at It and I4 lead the electric current to the apparatus, said current flowing from terminal l3 into hollow rod 4 and hence through contacts 2 and l to terminal M;

The operation of the circuit-breaker is as follows: By the operation through shaft l oi. the switch connecting rod unlocking insulator 9, spring l5, by displacing piston 6 towards the left, first separates contacts I and 2 and subsequently sparkingcontacts I and 2' momentarily held in contact by the second spring 19. On separation of said sparking contacts an arc is drawn out around which is projected the air contained in cylinder 5, said air being compressed by the rapid displacement of piston 6 which under the infiuence of spring l follows fiange I8. This air reaches the arc by flowing through apertures H in hollow rod 4 and then through the open passages-provided between sparking contact 2 and contact '2. Said air is conveniently guided around said are by converging nozzle 3 made from insulating material, and as this said nozzle also prevents the striking back of the are on to contact 2, said arc is rapidly extinguished.

After extinction of the arc, the displacement of piston 6 is arrested by abutting member l1, whereas rod 4 together with its contact continues its displacementaway from fixed contact I so as to provide between the contacts the insulating gap desired. This flnai displacement is very rapid for the reason that the comparatively important friction of piston 6 no longer intervenes. To damp the violence of the shock of the movable part against insulator 9 a damping device not shown in the drawing may be provided either inside or outside cylinder 5.

In this device, the whole of the compressed air is projected against the are along the path indicated by arrows in Fig. 2. These dispositions, whilst reducing the volume 01 air enclosed in the cylinder and in the rod, increase the pressure of the air and consequently that of the blast which is only produced during such time as is necessary for the extinction of the arc.

Having now particularly described and ascertained the nature or my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. In an electric circuit-breaker, a fixed contact and a movable contact, a pump to produce on separation of said contacts compressed air for the extinction oi the are, said pump comprising a cylinder, in the interior of said cylinder a piston, a rod, a projecting member fixed on said rod and a spring, said piston being mounted loosely on said rod and said spring being disposed so as to maintain said piston applied against said projectin'g member, said rod being extended outside said cylinder where it is provided with said movable contact, and an abutting member flxed in the interior of said cylinder, said abutting member being disposed so as to arrest the displacement of said piston before the termination of the displacement of said rod carrying said movable contact;

2. In an electric circuit-breaker, a fixed contact and a movable contact, a pump to produce on separation of said contact compressed air for the extinction of the arc, said pump comprising a cylinder, in the interior of said cylinder a piston, a rod, a flange flxed on said rod and a spring, said piston being mounted loosely on said rod and said spring being disposed so as to maintain said piston applied against said flange, said rod being extended outside said cylinder where it is provided with said movable contact, and an abutting member fixed in the interior of said cylinder, said abutting member being constituted by a cylindrical sleeve, the internal diameter of said sleeve being smaller than the external diameter of said piston and being greater than the external diameter of said flange.

LOUIS JOSEPH SAUDICOEUR. 

